Stabilization of organo-metallic agents



Patented June 19, 1945 OFFICE STABILIZATION OF ORGAN O-METALLIC AGENTS Harry W. Rude], Roselle Park, N. J., assignor to Standard Oil Development Company, a corporation of Delaware,

No Drawing. Application March 26, 1942, Serial No. 436,329

Claims. (Cl. 44-69) This invention deals with the protection of an organo-metallic agent, particularly with the protection of tetraethyl lead which is used in refined gasoline motor fuels as an anti-knock agent.

Thus far, tetraethyl lead has proved to he the most practical organo-metallic anti-knock additive. The gasoline fuels in which this additive is used have to be well refined to remove sulfurcontaining compounds which depress its effectiveness, but furthermore, it has been found desirable to overcome the tendency of this agent to become deteriorated by the action of light.

Investigations have shown that light breaks down tetraethyl lead and thereby forms a precipitate of lead compoundseven if the'tetraethyl lead is present in refined fuels which are stable toward oxidation or contain effective anti oxidants. For example, to obtain a true measure of the storagestability of aviation gasolines containing tetraethyl lead, it was found essential to protect the leaded gasoline samples from direct or diffused light before they are subjected to conventional accelerated gum tests. The deteriorating effect of light manifests itself formation of lead compound precipitates, and it has been found that this decomposition of the lead alkyl compound is accompanied by an aggravation of the objectionable corrosiveness that exist when moisture is present. This corrosivenew becomes apparent in the rusting of metal containers for the fuel, since it is diflicult to fully exclude moisture, and the aggravation .of the corrosive action may be ascribed to the electrolytic action of salts derived from the decomposed anti-knock agent which find their way into the moisture present with the fuel.

An object of this invention is to provide a protection against the undesirable action of sunlight on the organo-metallic compounds, such as lead alkyl compounds.

Another object is to prevent corrosive substances from being incorporated into fuels containing tetraethyl lead.

A further object is to preserve the clarity and stability of refined gasolines containing tetraethyl lead and to confer on the gasoline fuels an inertness to metals of fuel containers.

Objects of the present invention are satisfactorily accomplished by having present with an 'organo-metallic compound, such as tetraethyl lead, a small amount of a base metal salt of an aromatic sulfide. The preferred base metal con-' stituents of these salts are the alkali and alkaline-earth metals.

The preferred metal salts of aromatic sulfides by very rapid I degree of solubility in gasoline.

Salts of hydroxy-aromatic sulfides belonging to the class described may be represented by the fol lowing type formula:

wherein Ar indicates a substituted aromatic nucleus and M is the metal constituent linked thereto thru oxygen. Analogous compounds have the type formula M(XAr)2(S), wherein X represents, generically, a negative radical or atom.

The characteristic formulamay have a number of modifications, for'example, the aromatic radical may be monoor poly-cyclic; the number,

kind, and position of alkyl substituents in any of the aromatic nuclei may be varied; also, other substituent groups, e. g., amino groups, alkoxy groups, may be introduced.

The aromatic nuclei in the salts may be united thru a sulfide linkage containing more than one sulfur atom as in M(OAr)2(S)2, but the monosulfide linkage is preferred.

The metal salts of the aromatic sulfides may be prepared either by direct reaction of a base metal hydroxide or metal alcoholate with an acidic aromatic sulfide, e, g., a hydroxy aromatic sulfide or aroxy sulfide, if the metal constituent is strongly basic. If the metal is not strongly basic, or if the aromatic sulfide has a very weak acidic function, it is better to replace sodium in a sodium salt of the aromatic sulfide by the desired heavier base metal thru double decomposition with an alcoholic solution of its salt or its alcoholate.

As a specific illustration, the convenient methed for preparing the barium salt derivative of an aromatic sulfide is given in the following example:

(Di-isobutyl) -pheno1 sulfide (442 g.) is dissolved in 3 liters of pure benzene, and 331 grams of barium hydroxide octahydrate Ba(OH)2.8H2O,

are added. The mixture is refluxed for several hours in a flask fitted with a, condenser having a trap for removal of condensed water. The reaction mixture is filtered and the filter residue I added to hot benzene and refiltered. The two filtrates are combined and the solvent removed, yielding the salt bis (barium diisobutyl phenolate) sulfide as a yellowish pulverizable solid. The barium content of the salt was 22-23%.

It is an important advantage of the present invention that the described metal salts can be used in small quantities to accomplish the desired objects. They have been proved to be efiective in concentrations ranging from 0.01% to" 1% by weight with refined gasolines containing from /2 to about 3 cc. of tetraethyl lead per gallon for preventing the deterioration of the tetraethyl lead on exposure to actinic light radiations and in counteracting corrosion of iron, steel, and aluminum when the gasoline is wet.

The following data illustrates the efficacy of the described barium salt in a finished aviation gasoline containing 3 cc. of tetraethyl lead per gallon:

TABLE Tests on aviation gasoline containing 3 cc. of tetraethyl lead per gallon Corrosion-oi Concentration .Stee m of added Effects of sunlight exposure 855 55 123 pf added water for8 days Blank Precipitate in less than 1 hr. Severe. 0.002% Slight precipitation after 1 day Very slight. 0.04%. Slight precipitation after 8 days. None. 0.8% No precipitation after 8 days. Do.

I centrations will completelypr'event precipitation on exposure to sunlight. r

The compounds used in accordance with the present invention for stabilizing tetraethyl lead or similar'organo-metallic compounds are advantageously added to finished gasoline stocks which have been subjected to complete refining so that they satisfactorily pass the A. S. T. M. copper strip corrosion test for fuels, and are practically free of sulfurcontaining substances detrimental to the anti-knock effectiveness of tetraethyl lead. The gasoline fuel stock may be derived by cracking, or straight distillation, from liquefied petroleum gases, or from various synthetic reactions. In general, the gasoline should be purified to the extent that it is doctor sweet, contains less than 0.004% reactive sulfur, and shows no copper strip corrosion for 3 hours at 122 F. Compositions containing the stabilized organo-metallic agent may have incorporated increase the stability of the tetraethyl lead to the action of light, such salt having the composition indicated by the formula M(XAr)-AS) in which Ar indicates an aromatic nucleus, Mgis a metallic constituent selected from the class consisting of alkali metals, and alkaline earth metals, and X is a negative substituent selected from the class consisting of oxygen and sulfur.

2.A liquid composition containing tetraethyl lead stabilized against decomposition by an alkaline earth metal salt of a hydroxy-aromatic sulfide, said salt having the composition indicated by the formula M(XAr)2(S=) in which Ar indicatesan aromatic nucleus, M is an alkaline earth metal, and X isa negative substituent selected from the class consisting of oxygen and sulfur.

3. A composition comprising tetraethyl lead and his (barium diisobutyl phenolate) sulfide, to inhibit deterioration of the tetraethyl lead.

4. A composition as described in claim 3, in which the tetraethyl lead and said sulfide are blended with a refined gasoline which is practically free of sulfur-containing substances which are detrimental to the anti-knock effectiveness of tetraethyl lead.

5. The method of protecting a solution of an organo-lead anti-knock agent in gasoline against decomposition by actinic l'ght, which comprises incorporating in the solution a salt of an aromatic sulfide, said salt having the composition indicated by the formula M(XAr) 2(S) in which Ar indicates an aromatic nucleus, M is a metal selected from the class consisting of alkali metals and alkaline earth metals, and X is a negative substituent.

HARRY W. RUDEL. 

